JPH0282263A - electrophotographic photoreceptor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor for radar grinders.

[Conventional technology]

Conventionally, 1 helium was used in the photoreceptor of an electrophotographic printer that uses coherent light such as a radar beam as a light source.
Gas radars such as cadmium, argon, and helium-neon have been used, but recently semiconductor radars that are low cost and capable of direct modulation have come into use. Since this semiconductor radar generally has a failure wavelength of 750 nm or more, an electrophotographic photoreceptor with high sensitivity characteristics in the long wavelength region is required, and electrophotographic photoreceptors for this purpose have been developed. It's coming.

For this reason, a laminated type photoreceptor consisting of a charge generation layer and a charge transport layer, which can relatively freely select the photosensitive wavelength region, has been attracting attention as a photoreceptor for semiconductor radar printers.

The charge generation layer of a laminated photoreceptor has the role of absorbing light and generating free charges, and its thickness is as thin as 0.1 to 5μ in order to shorten the range of the generated photocarriers. It is customary. This means that most of the incident light is absorbed by the charge generation layer, generating many photocarriers, and the generated photocarriers are transferred to the charge transport layer without being deactivated by recombination or capture. This is due to the need for injection.

The charge transport material has the role of accepting static charges and transporting free charges, and uses one that hardly absorbs image-forming light.
Its thickness is typically 5-30μ.

When using such a photoreceptor and producing an image by scanning a line with a laser beam using a radar printer, there is no problem with line images such as characters, but in the case of solid images, density unevenness in the form of interference fringes appears. Ta.

The reason for this is that since the charge generation layer is formed of four layers as mentioned above, there is a limit to the amount of light that can be absorbed by this layer, so the light that has passed through the charge generation layer is reflected on the substrate surface.
This reflected light is further reflected on the surface of the photoconductive layer, which is thought to cause interference between the reflected light reflected on the surface of the photoconductive layer and another incident light that has passed through the surface of the photoconductive layer.

The laminated electrophotographic photoreceptor is shown in FIG. 1, which illustrates the structure of a conventional electrophotographic photoreceptor and the path of the radar light inside the photoreceptor when the radar light is incident on the photoreceptor. The structure is such that a charge generation layer 3 and a charge transport layer 4 are laminated on a conductive support 1 as shown in FIG.

When radar light 7 (oscillation wavelength is about 780 nm for a semiconductor radar and about 630 Ekm for a helium-neon laser) is incident on this laminated photoreceptor, the laser light 8 incident on the inside of the photoreceptor is transmitted to the conductive support. This reflected light 9 is further reflected on the surface of the charge transport layer 4, and interference occurs between this reflected light 10 and the incident light 8' of another radar light 7'.

In the conventional electrophotographic method using radar light, for example,
% Publication No. 186850/1983, Japanese Patent Application No. 172/1983
047, JP 60-252359, JP 61-240247, JP 59-24853
No. 1, JP-A-60-256143, JP-A-62
As disclosed in Japanese Patent No. 299857, the surface of the substrate is roughened, carton powder is added to the undercoat layer, or ffDF resin is added to the conductive layer to conduct radiation.
By absorbing or diffusing light, the occurrence of density unevenness in the form of interference fringes was prevented.

[Problem to be solved by the invention]

However, such conventional methods may cause image defects,
There were major problems with electrophotographic properties such as durability. In other words, when the surface of the conductive layer is roughened by adding PVDF resin to the conductive layer, which is based on the substrate surface, local defects occur, resulting in image defects such as black spots and white spots on the image. . In addition, when Karzan powder is added to the undercoat layer or conductive layer, the charge injection property increases, and the surface potential of the photoreceptor does not reach the specified value, resulting in density soot and white spots in normal development, and ground density in reverse development. Defects such as yellow spots and black spots occurred.

The object of the present invention is to provide a photosensitive member that eliminates the drawbacks of the prior art described above, in particular, by absorbing excess laser light in the undercoat layer, without the need to roughen the substrate and laminated interfaces. Radar that prevents density unevenness like interference fringes
An object of the present invention is to provide an electrophotographic photoreceptor for printers.

[Means to solve the problem]

The electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor formed by laminating an undercoat layer and a photosensitive layer on a conductive support, wherein the undercoat layer contains a charge generating material and the undercoat layer contains a charge generating material. It is characterized in that the laser light transmittance of the layer is 40% or less.

The present invention will be specifically described below with reference to the drawings.

Figure 1 shows an example of the structure of a conventional electrophotographic photoreceptor and a radar.
It shows the path of radar light inside the photoreceptor when light is incident. FIG. 2 shows the electrophotographic photoreceptor of the present invention and the path of the radar light inside the photoreceptor when the radar light is incident thereon. In the figure, 1 is a conductive support, 2 is an undercoat layer,
3 is a charge generation layer, 4 is a charge transport layer, 5 is a support, 6 is a conductive layer 7 and 7' are incident laser beams, 8 and 8' are incident laser beams into the inside of the photoreceptor, 9 is a conductive support 10 represents the light reflected from the body surface, 10 represents the light re-reflected from the surface of the charge transport layer, and 11 and 11' represent the radar light incident on the undercoat layer.

As shown in FIG. 2, the electrophotographic photoreceptor of the present invention includes, on a conductive support 1, an undercoat layer 2 and a charge generation layer 3, each having a transmittance of 40% or less for the wavelength of the radar light source used. A charge transport layer 4 is laminated. The charge generation layer and the charge transport layer may be stacked in the reverse order.

The conductive support 1 may be a single body 1 having conductivity itself, or may have a laminated structure having a conductive layer 6 on the support 5. In this case, the support 5 may be conductive or non-conductive.

For example, as a conductive support, an aluminum cylinder or an aluminum sheet can be used, and as a non-conductive support, a polymer film or cylinder, or a knot material such as paper, glass, or metal can be used.

Regarding the conductive layer 6, as a resin for dispersing conductive pigment powder and, if necessary, particles for forming surface irregularities, the resin must have strong adhesion to the substrate, good dispersibility of the powder, and solvent resistance. Any material that satisfies conditions such as sufficient properties can be used, but thermosetting resins such as curable rubber, polyurethane, epoxy resin, alkyd resin, polyester, silicone resin, and acrylic-melamine resin are particularly suitable. be.

The volume resistivity of the resin in which conductive powder is dispersed is 10150.
A suitable resistance is less than 10Ω, preferably less than 10 12 Ωα. In the round coating film, the conductive powder has KIO~60 in the coating film.
It is preferable that it is contained in a weight ratio.

K for dispersing conductive powder into resin is roll mill, retraction? - Lumill, attritor It can be carried out by a conventional method such as a sand mill or a colloid mill.

When the substrate is in the form of a sheet, suitable coating methods include high wire percoat, blade coat, knife coat, roll coat, and screen: I-tonato tbx.
Dip coating is suitable when the substrate is cylindrical.

Charge generation No. 3 is Sudan Red and Diane Blue.
Azo pigments such as Zenasgelin B, Al f −/l/
(Yellow Billet/Quinone, Indanthrene Brilliant Piole,) Quinone pigments such as RRP, quinocyanine pigments, perylene pigments, Insogo pigments such as Innoco 0 and Thioinnovo, Bisbenzimidazole pigments such as Indofast Olene Toner, Steel Phthalocyanine,
It is formed by dispersing a charge-generating substance such as a 7-thalocyanine pigment such as aluminum chloride phthalocyanine or a quinacridone pigment in a styrosifying resin such as polyester, polystyrene, polyvinyl butyral, polyvinyl pyrrolidone, methylcellulose, polyacrylic acid ester, or cellulose ester. .

The composition of the charge generation layer is preferably 20 to 3001 i[s] of the binder resin based on 100 parts by weight of the charge generation substance.

As a method for dispersing the charge-generating substance, a conventional method using a roll mill, a gall mill, an attritor sand mill, a colloid mill, etc. can be employed. The average particle diameter of the charge generating substance during dispersion is preferably 0.01 to 1.0A. Dispersion a is applied by wire/4-coat, blade coat, knife coat, roll coat, screen neat, spray coat, dip coating, etc., and the organic solvent is volatilized by a conventional method such as heating and drying. to form a charge generation layer. Film thickness is 0.05-1
．． A range of 0μ is desirable.

The charge transport layer 4 has a main chain or a side chain containing a polycyclic aromatic compound such as anthracene, pyrene, phenanthrene, coronene, or indole, carbazole, oxazole, inoxazole, thiazole, imidazole, pyrazole, oxadiazole, pyrazoline, theanoazole, It is formed by dissolving or dispersing a charge-transporting substance such as a compound having a nitrogen-containing cyclic compound such as triazole or a hydrazone compound in a resin with film-forming properties, applying a coating solution, and drying. The thickness of the charge transport layer is preferably 5 to 20 microns.

In the present invention, an undercoat layer is provided below the charge generation layer.

The undercoat layer is made of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid co-limer, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. It can be formed by

The present invention is characterized in that instead of incorporating a charge generating material into the undercoat layer to absorb excess radar light, the undercoat layer has a radar light transmittance of 40% or less. . Such charge-generating materials include cyanine-based, merocyanine-based, triphenylmethane-based, biryllium base, thiopyrylium salt-based dyes, azo-based, phthalocyanine-based, etc.
Examples include bisbenzimidazole pigments, and particularly preferred are cyanine dyes, azo pigments, and 7-thalocyanine pigments.

In the present invention, preferably 10 to 40% by weight of the above charge generating material is mixed into the undercoat layer.

As for its compounding method, the above-mentioned charge generating material is added to the above-mentioned undercoat layer-forming material and thoroughly dispersed with one or more organic solvents using, for example, a sand mill.

Using this liquid mixture, a resin film is formed on a conductive support by a method such as a bar code or dip coating. The film thickness is 0.1
~5μ, preferably 0.5μ to 3μ is suitable.

In an electrophotographic photoreceptor characterized by having such an undercoat layer, since the undercoat layer has a low laser light transmittance, K, that is, the roundness absorbed in the undercoat layer is 1 as shown in the fs2 diagram. The nine-day light incident on the photosensitive layer is 8.11 (8
', 11') has a low reflection rate on the surface of the conductive support, and no density unevenness due to interference fringes can be seen on the image.

The present invention will be explained below by way of examples. In the description of the Examples, all parts are by weight.

Example 1 100 parts of conductive titanium oxide powder, 1 part of white titanium oxide powder
00 parts and 125 parts of the phenol resin were added to a mixed solvent of 50 parts of methanol and 50 parts of methyl cellosolve, and then dispersed in a Gehl mill over a period of time.

60% of this dispersion. It was coated on an aluminum cylinder with a diameter of 260 m1 by a dipping method and thermally cured at 150°C for 30 minutes to form a conductive layer with a thickness of 20 μm. The surface roughness on this conductive layer was 1.5μ.

Next, 10 g of alcohol-soluble copolymerized nylon resin (average molecular weight 29,000), 30 parts of methoxy 7-methylated 6 nylon resin (average molecular weight 32,000) and 4 parts of ε Steel Phthalocyanif were added to 260 parts of methanol and 40 parts of butanol.
In addition to the fflS mixture, the mixture was dispersed for 2 hours in a sand mill using 1.0 ffill φ glass beads. This liquid mixture was dip coated onto the conductive layer to form a 1 μm thick undercoat layer. Note that the transmittance of the undercoat layer at this time for light having a wavelength of 780 nm was 35%.

Next, add 100 parts of VC# type steel phthalocyanine, 50 parts of tutilal resin and 1350 ffli of cyclohexane to 1 O
The mixture was dispersed for 200 hours in a sand mill using tmφ glass beads. 72,700 parts of methyl ethyl keto was added to this dispersion, which was applied onto the undercoat layer by dip coating, and dried by heating at 80°C for 10 minutes to give a coating of 0.15? A charge generation layer was provided with a coating amount of /m2.

Next, 10s of the human 2-sine compound of structural formula (1) and 15 parts of styrene-methyl methacrylate copolymer resin were dissolved in 80 parts of toluene.

This liquid was applied onto the charge generation layer and dried with hot air at 100° C. for 1 hour to form a charge transport layer with a thickness of 16p.

This laminated slightly photosensitive drum was attached to an experimental radar printer (charged with negative polarity) having a gallium-aluminum arsenide semiconductor radar (emission wavelength: 780 nm, output: 5 mW), and an image was formed using a reversal current method.

As a result, an image with uniform image density in the peta image area and sharp line images was obtained.

Comparative Example 1 A comparative photosensitive drum was prepared by forming a conductive layer, an undercoat layer, a charge generation layer, and a charge transport layer in the same manner as in Example 1 except that C-type copper 7 talocyanine was not used in the undercoat layer. .

When this comparative photosensitive drum was attached to the same experimental radar printer as described above and an image was produced, there was no problem with the line image, but uneven density occurred in the peta image area due to interference.

Example 2 A conductive layer was provided in the same manner as in Example 1. Next, 10 parts of copolymerized nylon and 4 parts of the azo pigment of structural formula (2) were added to a mixed solution of 80 parts of methanol and 55 parts of butanol, and the mixture was dispersed for 2 hours using a sand wheel using glass beads of 1.01 alφ. . This liquid mixture was dip coated onto the conductive layer to form a 1 μm thick undercoat layer. Note that the transmittance of the undercoat layer at this time for light having a wavelength of 780 nm was 30%.

Further, a charge generation layer and a charge transport layer were formed in the same manner as in Example 1 to obtain an electrophotographic photoreceptor.

An image was formed on this photoreceptor in the same manner as in Example 1, and an image with a uniform pattern density and a sharp line image was obtained.

Comparative Example 2 A conductive layer, an undercoat layer, a charge generation layer, and a charge transport layer were formed in the same manner as in Example 2, except that the compound of structural formula (2) was not used in the undercoat layer, and a comparative photosensitive drum was prepared. Created.

When this drum was attached to the experimental radar printer mentioned above and an image was produced, there was no problem with the line image, but a striped pattern due to interference appeared in the peta image area.

Example 3 The charge generating material in the undercoat layer in Example 1 was expressed by the structural formula (
3) A photoreceptor drum was prepared in the same manner as in Example 1 using the azo pigment KL and other conditions, and when an image was produced, a uniform peta image and a sharp line image were obtained.

Comparative Example 3 A photosensitive drum was prepared in the same manner as in Example 1, except that the charge generating material in the undercoat layer of Example 1 was replaced with 5 parts of carbon powder. Furthermore, when images were produced using the same method as in Example 1, no interference fringes were observed, and 9 was a solid white image with black spots. In a photoreceptor having such a subbing layer containing carbon, the carbon powder has a tendency to inject seven-lead carriers, and it is considered that image defects are likely to occur.

[Effects of the Invention] According to the electrophotographic photoreceptor of the present invention, clear electrophotographs can be obtained without interference fringe-like density unevenness after image exposure and development.

This effect is particularly remarkable when coherent light, especially Radhe light, is used as a light source for image exposure), and it can be extremely advantageously applied as an electrophotographic photoreceptor for Radheon printers.

Furthermore, unlike conventional methods in which the substrate of the photoreceptor or the laminated interface of the photosensitive layer is roughened, the surface condition is smooth, so there are extremely few defects.

Therefore, the image quality is improved, and image gII decreases by 11 degrees after repeated durability, toner fusion to the photosensitive drum, and pinholes do not occur.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of the structure of a conventional electrophotographic photoreceptor and the path of laser light inside the photoreceptor when laser light is incident thereon. FIG. 2 is a schematic diagram showing the electrophotographic photoreceptor of the present invention and the path of radar light inside the photoreceptor when laser light is incident thereon. In the figure, l is a conductive support, 2 is an undercoat layer, 3 is a charge generation layer, 4 is a charge transport layer, 5 is a support, 6 is a conductive layer, 7 and 7' are incident radar lights, 8 and 8' is the radar light incident on the inside of the photoreceptor, 9 is the reflected light on the surface of the conductive support, and 10 is
is the re-reflected light on the surface of the charge transport layer, and 11 and 11' are the radar lights incident on the undercoat layer.

Claims (1)

[Claims] In an electrophotographic photoreceptor formed by laminating an undercoat layer and a photosensitive layer on a conductive support, the undercoat layer contains a charge generating material, and the undercoat layer has a laser light transmittance of 40.
% or less.